Iron ore is aound 5g per on my server, which makes your cost around 9k, assuming you don't use an xmute-spec alchy, which would be a bit silly. Just yesterday I was xmuting ghost iron ore and had 4 consecutive procs, 3 of 2 trillium bars and one of 4 trillium bars.

So if using an xmute-spec alchy, you should need around 25% less material to make the breatplate, reducing the cost to around 7,200g plus Spirits.

Spirits are probably costly - I haven't been in the market for crafted items requiring them, but the drop rate is pretty low.

It's certainly costly, but if you have boatloads of gold, what does it matter? The most expensive part of any xpac is the initial gearing to raid if you don't want to wait for drops.

If you're not a BS then it's considerably more problematic. I've crafted myself a chest and going to craft gloves when I farm another mote, but I like having all the gear I can possibly have RIGHT NOW, regardless of what drops in raid.